399421440 has 312 divisors, whose sum is σ = 1518021648. Its totient is φ = 96337920.

The previous prime is 399421417. The next prime is 399421441. The reversal of 399421440 is 44124993.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 399421395 and 399421404.

It is not an unprimeable number, because it can be changed into a prime (399421441) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2027422 + ... + 2027618.

It is an arithmetic number, because the mean of its divisors is an integer number (4865454).

Almost surely, 2^399421440 is an apocalyptic number.

399421440 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 399421440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (759010824).

399421440 is an abundant number, since it is smaller than the sum of its proper divisors (1118600208).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

399421440 is a wasteful number, since it uses less digits than its factorization.

399421440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243 (or 218 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 399421440 is about 19985.5307660317. The cubic root of 399421440 is about 736.4508894405.

The spelling of 399421440 in words is "three hundred ninety-nine million, four hundred twenty-one thousand, four hundred forty".